The invention relates to improvements in electromagnetic crosspoint switches, particularly for optical transmission.
Several proposals have been made in the past involving an optical crosspoint array which employs acoustic-optic interaction for selectively deflecting an input beam of light energy propagating along the axis of an optical channel. Such channel is conventionally defined, e.g., on a substrate-supported film.
Each of such proposed acoustic-optic arrangements has one or more disadvantages. In one technique, for example, separate piezoelectric transducers must be affixed to the lateral edges of the substrate at each of the crosspoints; this leads to a complicated and bulky assembly.
In another of such arrangements, the input and output channels are individually defined in parallel fashion on opposite surfaces of a common substrate. In addition to the complex processing steps necessary for this, such design requires for its switching operation the physical movement of a pair of beam-guide couplers that are disposed at the opposite surfaces of the substrate.
Optical crosspoint matrix designs using magneto-optic conversion have also been proposed. These designs have contemplated the use, at each crosspoint, of at least one directional coupler to extract only a portion of the incident energy for processing through the array. The insertion loss exhibited by such scheme is relatively large and cumulative over the path of propagation of an optical beam through the device.